The present invention relates restraining of devices and, more particularly, to an apparatus for restraining the upper portion of a child seat that has been itself mounted on the seat of an automobile or other vehicle. More specifically, the invention relates to an apparatus for yieldably restraining the upper portion of a child seat such that the shock applied to the occupant of the child seat in the event of a crash or the like is reduced.
A child seat comprises a sitting portion on which the buttocks of the infant or child rest and a back portion against which the back of the infant or child leans. The sitting portion and the back portion are typically unitarily formed therewith. The occupant of the child seat is restrained by restraining equipment (such as a seat belt for children) provided on the child seat.
The typical child seat is itself fixed to the vehicle seat by an adult seat belt. When fixing the child seat on the seat with an adult seat belt, the necessary procedures of pulling the seat belt and passing it through or hooking on the prescribed portions of the child seat can be troublesome. In addition, it expends much effort to carry a child seat into the cabin of the vehicle because the child seat is bulky.
European Patent Application No. EP 841209 A1 discloses a system in which bearing seats formed of rods are mounted on the left and right sides of the seat of the automotive vehicle so that a child seat is detachably mounted on the rear. The child seat of this type comprises two longitudinal members extending rearward, and the tips of the longitudinal members are provided with engaging portions to be engaged with the bearing seats. The left and right sides of the child seat are provided with arms being rotatable in the back and forth directions, so that the isolation of the child seat from the vehicle seat is prevented by the abutment of the arms against the seat back of the vehicle seat.
In case of a frontal crash (including an offset crash, same applies hereinafter) of the vehicle, a large force in the forward direction is applied to the child seat being mounted forward-facing on the vehicle. With the lower part of the child seat fixedly restrained to the seat, a frontal crash generates a rotational force causing the child seat to turn forward, so that the upper portion of the child seat inclines forward.
To prevent the rotational movement of the upper portion of the seat, one possibility may be to connect the upper portion of the child seat to a vehicle member located behind the seat. However, when the upper portion of the child seat is connected to the vehicle member, the shock applied by the child seat restraining equipment (webbing for children or the like) to the child seat occupant may increase in case of a frontal crash.
Accordingly, an object of the present invention is to provide an apparatus for restraining the upper portion of the child seat that can reduce the shock applied to the child seat occupant.
A child seat restraining apparatus of the present invention has an extensible energy-absorbing device that is intended for yieldably supporting the upper portion of the child seat that is mounted facing forwardly on the seat of the high speed mobile body and attached to a fixed body portion behind the child seat. When a forward stress in excess of a prescribed value is applied to the child seat, the device increases the distance between the upper portion of the child seat and the fixed body while absorbing the stress.
In such a child seat restraining apparatus, when a stress in excess of a prescribed value is applied, the upper portion of the child seat moves forward while the apparatus absorbs the stress, so that a shock applied by child seat restraining equipment to the person sitting on the child seat decreases.
As to a general aspect of the invention, the apparatus comprises an extensible energy-absorbing device having a movable portion adapted to increase the effective length of the device upon application of a tensile stress in excess of a prescribed value to the device, a seat-engaging element operatively connected to one of the movable portion of the energy-absorbing device and adapted for attachment to the upper portion of the child seat, and a vehicle-engaging element operatively connected to the movable portion of the energy-absorbing device and adapted for attachment to the fixed body portion of the vehicle.
As a mechanism for absorbing the shock, the energy-absorbing device may take the form of, e.g., a metal member that absorbs the stress by becoming deformed by the stress, a tether belt having tear seam, or a tether belt woven so as to be stretched while absorbing a stress.
When a metal member is used, variation in the breaking strength of metal is not significant, and it is relatively simple to set the stress absorption strength.
When a tether belt is used, a stress absorbing means may be provided directly on the tether belt. If so provided, it is not necessary to provide an additional stress absorbing device, thereby decreasing the number of components. It is also possible to use a conventional tether belt combined with a stress-absorbing feature.
When using a tether belt woven so as to be stretched while absorbing a stress, a stress absorbing feature may be provided by changing the weave of the tether belt itself. If so provided, it can be used as a specific tether belt for absorbing the stress, thereby reducing the number of the components. Time and effort in providing a tear seam can be saved.